1. Field of the Invention
The present invention relates to a camera having a powered zoom lens and, more particularly, to a powered zoom lens camera having a depth-of-field priority zoom mode.
2. Description of Related Art
In recent cameras, various photographic techniques have been automatized. One example is a depth-of-field priority mode which coordinates the necessary tasks related to focusing when a plurality of objects are to be taken. More specifically, in this depth-of-field priority mode, two or more objects at different object distances are in focus.
In one known camera having such a depth-of-field priority mode, the different object distances are stored in a memory after both the focusing operations and the object distance measuring operations, or after only the object distance measuring operations, have been carried out by an automatic focusing device for the different objects in the composition. Thereafter, the brightness of the objects is measured by a photometer to determine optimum exposure values, and the optimum exposure values are input to a control unit of the camera together with the focal length data. From there, based on the data input thereto, the control unit performs arithmetic operations for obtaining the focused object distance and the diaphragm value so that the objects can be made to fall within the depth of field.
However, in the camera mentioned above, only the focused object distance and the diaphragm are controlled. Therefore, it is very difficult to accurately bring the objects of different object distances into focus, particularly in the cases where a photographic lens with a long focal length is used, an object at a close distance is to be photographed, or a dark object is to be photographed.